Press fluid control unit



Aug. 26, 1941.. s. T. WILLIAMS 2,253,544

' PRESS FLUID CONTROL UNIT n Filed May 2o, 1959 2 s'meets-st xeet` 1|NvENToR Filed May 20, 1959 2 Sheets-Sheet 2 i u m A. 4 m 0 n MvwwEwMm/H m. Wm au w. o 0V ao N v n 0V av du A M Y. g y mn; 7 i Mw j@\.W\JV0Q o AVMQV 00 M WM @l 0 n |M l. 6 u@ J MW@ M5 M7 WMV ,WIM .1.0 nv0Patented Aug. 26, 1941 PRESS FLUID CDNTBOL UNIT I semen T. Williams,neuer-ose, N. Y., assignor to Scovill Manufacturing Company, Waterbury,

Con/11 a corporation of Connecticut Application May 20, 1939, Serial No.274,689

9 Claims. (Cl. 121-38) safety engineers and labor boards, and much hasbeen done to reduce the hazard to personal injury incident to pressoperations. Various forms of safety appliances in the nature of safetyclutches, electrical devices, and mechanical shields have been devised,and while these have met with varying degrees of success andrecognition, on the whole they have been open to one objection oranother. Among the primary objections met with by these safety devicesare: (1) their tendency to slow down the press opera- -tion; v(2) theirhigh installation cost; (3) their non-foolproof character; and (4) theirsafety characteristics could 'be circumvented by an operator who desiredto speed up production.

My present invention provides a safety device for power presses and thelike which overcomes the various objections and limitations abovementioned. In its underlying concept my invention relies upon compressedair to operate a plunger for tripping a clutch on the drive shaft of thepress or for operating an equivalent means, and a plurality of controlvalves so disposed with relation to the operating head of the press thatboth hands of an operator must be used to operate saidA valves and bewell away from the danger zone when doing so; and further, said valvesare shielded so that 'they' can not be accidentally operated.

With the safety device described in my copending application referredto, it has been found that if the normal operating conditions shouldvary, so that the air pressuresuddenly falls, the puff of air which isadmitted to the trip plunger operating cylinder isnot always suflcientto insure the tripping action. Hence, according to my present inventionI rely upon a continuously acting pressure` to operate the tripplungerand I provide a normally spring-seated pilot valve adapted to beunseated by a pilot-operating means, which, in turn, can be operated bya puff of compressed air at much lower pressure than is necessary tooperate the plunger for tripping aclutch. I also rely upon the movementof the Ypiston in the clutch-operating cylinder to re' leasethepilot-operating means whereby to permit the pilot valve to shut offthe supply of air pressure to the operating cylinder, and, in turn, ventthe compressed air from the operating cylinder to the atmosphere.

-The principle, construction and operation of my improved safety controldevice will be better understood from the detaileddescription whichfollows, when considered in connection with the accompanying drawingswhich show a practical embodiment of my invention, and wherein:

Figure 1 is a perspective view of a power press, showing my inventionapplied thereto.

Fig. 2 is a longitudinal section through one of the manually operablevalves forming a part of my invention.

Fig, 3 is an axial section through a cut-out valve forming a part of myinvention.

A in Fig. 4.

Although my invention is capable of use with any type of press ormachine which has a movable head adapted to move toward and away from acomplemental member and between which members the hands of an operatormust be positioned in the handling ofthe work to be operated upon by-lthe machine, I have shown my safety device applied to a power press A oiconventional design having a movable head I0 which carries a die I I`for cooperation with a complemental die I2 mounted ,on vthebase of the'press. The head I0 is reciprocable so as vto bring the dies II and I2Ainto operative position to the work being acted upon, and reciprocationof the head being provided by rotation `of a shaft I3 upon which isdanger, I have provided a pair of manually operable valvesl B and ,acut-out valve Cwhich form part of a pneumatic circuit adapted to supplya puff'of compressed air into a cylinder I8 of a pilot valveoperating'means D for unseating a pilot valve E to admit compressed airfrom a source directly into the clutch-operating cylin- A.

der Il.

The manually operable valves Bare identical in construction and eachconsists of a hollow casj ing I9 having lateral tubular offsets orprojections 20 and 2| providing induct and educt openings, respectively,in the casing. Within the casing between the lateral oil'sets is a.shoulder upon which is mounted a valve packing seat 22 which is held inplace by a tubular plug 23 having lateral openings 24 therein, the saidplug being screw-threadedly or otherwise held in position within thecasing. Mounted within the casing for engagement with the packing seat22 is a valve check member 25, the lower portion of which is hollowedout and encloses a helical spring 26 for normally holding the valveagainst its seat. The valve check 25 above theseating portion thereof isformed with an axial pin 21, the upper end 28 of which is'of tubularform and of a diameter to snugly slide through the axial opening in thetubular plug 23, and said tubular portion of the pin at its lower end isformed with lateral openings 29. To insure against leakage and toprovide an air seal between the top of the tubular plug 23 and the topof the hollow portion 28 of the valve pin 21 I connect said partstogether by a cone-shaped packing 30. Any suitable means may be employedfor holding this packing in contact with said parts, and as hereinshown, the packing which is formed as a separate part, has a sliding twith the hollow portion of the valve check pin and Iis held in clampingengagement with the tubular plug -23 by a tubular member 3| whichscrew-threadedly engages within the casing I9. Mounted for tele'- scopicmovement Within the tubular member 3| is a plunger 32, the inner end ofwhichvis recessed, as at 33, to engage over and seal the open end of thehollow portion of the valve check pin when the plunger is depressed inthe act of unseating the valve check 25. The plunger 32 is of a lengthto extend beyond the top of the tubular member 3| and is normally urgedoutwardly by a helical spring 35 mounted between a shoulder within thetubular member 3| and a shoulder' on the plunger 32 for limiting theextent of the plunger movement. `For holding the plunger 32 againstseparation from the tubular member 3|, the plunger is formed with a slot36 through which extends a pin 31 carried by the tubular member. Forfacilitating movement of the plunger by the hand of an operator, theplunger at its outer end is provided with an enlarged mushroom head 34.The tubular lateral offsets 20 and 2| are each threaded for connectionwith screw-threaded nipples 38 attached to sections of hose or flexibleconduits 39 forming a part of the pneumatic circuit. The tubular member3| is also formed with a lateral opening or vent 40, which, it will beobserved, provides .open communication through the tubular portion 28 ofthe valve check pin and the lateral openings 24 in the tubular plug 23,with the bore through` the lateral oiset 2|, when the check valve 25 isseated. When the valve check 25 is unseated it will be apparent thatthis open communication is cut oi by the seal provided by the engagementof the lower end of the plunger 32 with the coned packing 30.

The cut-out valve C consists of a casing formed of a central,substantially' cylindrical element 4|, the ends of which arescrew-threadedly connected to tubular end members 42 and 43, each ofwhich terminates in an outwardlydirected nipple 44 to which an end ofthe conduit ,or house .39 is suitably connected. Mounted within thecasing provided by the elements 4|, 42 and 43, is a tubularl member 45having a bore substantially ilush with the bore through the nipple endof the element 42 and having an outwardly-directed flange 48 which isclamped against a flat surface in the element 42 by the screw-threadedconnection between said elements 4| and 42. Surrounding the tubularelement 43 in slightly spaced relation thereto is a tubular plungercheck valve 41, which, at its end adjacent the flange 48, is formed witha flange 48 and carries a piston packing 49 having a diameter toair-tightly move within the cylindrical bore of the element 4|.

.Surrounding the plunger check valve 41 and bearing at one end againstthe flange 48 is a helical spring 50, the opposite end oi which bears.against an inwardly-directed ilange 5I on the tubular element 4| forthe purpose of exerting a force upon the plunger valve for normallyholding it in its unseated position, as shown in Fig. 3. The plungervalve 41at its other end is closed and formed with an annular ring 52,rearwardly of which the plunger valve is formed with lateral openings 53leading from the interior of the tubular plunger to the duct through thecut-out valve. The closed end of the plunger valve is adapted to engagea valve seat packing 54 mounted within the tubular element 43 and heldtherein by a sleeve 55 which is clamped between the annular ilange 5|and said packing in the assembly of the elements 4| and 43, there beingalso provided a packing 58 between the sleeve 55 and the ange 5|, whichpacking engages the outer wall of the plunger valve 41 to provide anair-tight seal therewith. The packing 54 consists of two washers which-are pressed over a tubular sleeve 51 having an outwardly-directedilange or rib 58 intermediate its ends. The element 43 between thenipple 44 thereon and the packing 54 therein is'formed with a chamber'having a spider 59 for guiding the stem of a valve 6U, the face thereofwhich engages the packing 5,4 being of conical form and of smallereiective area than the opposite face of said valve. The function Iforthis construction will presently be explained. To prevent tampering withthe cut-out valve parts they are housed within a shell 60a having a ventopening 60h. The tubular element 4| also has a vent opening 4| a forpermitting the venting of any air under pressure which may iind its wayinto said element.

The pilot valve operating mechanism D, the pilot valve E, and theclutch-operating cylinder |1 are all supported upon a base plate orcasting 6l which is pivotally mounted to the press frame at 62. The baseplate or casting 8| is o1' such form as to constitute one head 63 of thepilot cylinder I8, one head 64 of the piston-operating cylinder |1, andthe housing and support 65 for the pilot valve E.

The pilot cylinder I8 has a top closure head 86 of larger area than thecylinder |8 and is clamped in air-tight engagement therewith throughsuitable bolts 61, said head having an induct passage 68 in opencommunication with the pneumatic circuit which includes the valves B,the cut-out valve C and the conduit sections 39. Within the pilotcylinder I3 is a piston plunger 69 carrying a piston packing 10, thepiston having axial extensions 1| and 12 on either side thereof,respectively. Encircling the piston extension 12 is a coil spring 13which bears at one end against the cylinder head 53, and at its oppsiteend against the piston 69, and normally acts to urge said pistonupwardly, and is -limited in this action by engagement of the extension1| i Y 2,253,544 with the head sa. YThe head sa has im um vopening 14therein through which the piston extension 12 may pass when the pistonis subjectedY toA air pressure. The free endV portion .of the extension12 is ofv reduced diameter and provides the downward movement of thepiston withinA the cylinder.. Y

Mounted' within the base plate or casting 6I below the head 63 is abell-crank lever 'I5 having arms 'I6 and I'l and being pivotedsubstantially at the intersection of said arms at 18. The arm 11 at itsfree end is bifurcated and 'has pivotally mounted thereto Aa -trip bar19, one end 80 of which extends below and in substantially para shoulderwhich serves to limit the extent of against the housing 65 'and beingheld in said position by a lock nut. Also carried by the housing 65 inabifurcated lug thereon, is a lever |06v which is pivoted at I 01 forlimited movement, the

-free end of said lever being disposed between one end of the trip bar'|9 and the ball valve 89, the said lever |06 being limited in itspivoted action and serving'to hold the ball valve from dropping allelrelation to the arnr 16, and the portion of the trip bar to the oppositeside ofthe pivot extends below and across the axis of the cylinder head.64. Mounted between the arms 16 and 8011s, a

compression spring 8| which normally tends to urge said arms apart intotheir'normal position, as shown in Fig. 4. 1 j

'Ihe housing -or bodyv 65 of the pilot valve E is formed with variousopenings and passages therein, one of'which, 82, isinternallyscrewthreaded and accommodates a screw .nut 83 which has anaxial passage therethrough, and at.

its inner end isl provided with .an external shoulder which supports apacking gasket 84,

which constitutes the seat for av valve check 85, the stem 86 of whichslidably extends through the axial .opening in the screw nut. The screwnut 83 adjacent the packing gasket 84 is formed outer atmosphere. Thevalve stem 86 also'has av transverse passage 90a at the inner end of thebore for establishing communication between the bore inthe stem and theaxial passage through the screw nut 83. For guiding the valve stem. andfor insuring a leak-tight sliding t between it and the bore through thenui'l 83, the-latter is provided with a packing washer 9| and a lockscrewA 92. 'Ihe valve check 85 at its innermost end is formed with anaxial projection 93 for supporting a coil spring 94 which normallyserves to hold the check valve upon its seat. 'Ilhe pilot valve housing65 is also formed with an internal chamber 95 in open communication withthe passage through an adapter nipple 96, to which is connected aconduit 91 leading from a source of compressed air. The housing 65 isalso formed a chamber 98 which is in open communication with an adapternipple 99 to which is secured a tube or conduit |00, the opposite endofv which connected through a suitable nipple adapter 10|' with theinterior of the cylinder I'l through suitable openings in the head orcover plate |02.

The cover plate suitably holds the'cylinder in leak-tight engagementwith the head 64 by suitable bolts I03. The housing-65 is supported inthe base plate or Acasting 6I through the medium of bolts |04, and isdefinitely located within said base plate by adjustment ofv a locatingvbolt |05 extending through a bracket I05a secured to said base plate,the head of the bolt |05 Vbearing out-of the valve stem. while at thesame time' permitting the unseating of said ball valve.

l 'I'he cylinderhead |02 has an axial passage therethrough within whichis mounted a gland packing |08 for insuring against air leakage from thecylinder around the' plunger rod I5. gland packing isA held in place byva, screwthreaded plug |09'which also serves as a bearing for one end ofa compression spring Ifll mounted on the rod I5, the other end of thespring bearing against a collar III which is adapted to be held in xedposition on the rod I5.

The piston I6 consists of a disk-like member having a iiat top face uponwhich is mounted a suitable packing cup H2 adapted for slidingleak-tight engagement with the inner wall of the i cylinder I1, thesaidl cup being held on the disk by a clamping plate II3, and a clampingnut H4 of the valves B.

which'screw-threadedly engages over an axialV tubular bushing I|5 on thepiston disk. The Atubular bushing also extends downwardly beyond theopposite sideof the disk and constitutes a projection which is adaptedto 'pass through an axial opening I I6 in the piston'head 64 to engagethe trip bar 19 to release the lever |06 and permit the valve check 85to seat'under the tension 'of the spring 94.

The manually operable valves B vmay be conveniently attached to themachine byfmeans of brackets II1 which are Abolted to the ends of thebed of the press. These brackets may also conveniently carry shields II8which extend above and partially encircle The device hereinbeforedescribed is primarily intended for operation in connection withrepeating type clutches to insure but a single operation of the press. 1

Operation.-With .the parts assembled and adjusted so that vthe admissionof compressed air into the cylindervi will move the plunger I6 in-Wardly against the tension of the spring ||0 and trip the clutch so vasto permit the'press head I0l to move downwardly, the operation of thedeviceV for press control is as follows:

Ihe ri'ght hand operating Valve'B must be Y pressed down slightly inadvance of the left vhand Valve B or substantially simultaneouslytherewith. When this is done, compressed air from the source'passes'through the pneumatic circuit into the cylinder I8 of the pilotvalve operating means and Iorces the piston therein downwardly,.whichaction causes a rocking of the bell-crank 'I5 against the tension ofspring 8| and moves the tripbar 19 to the right, thereby moving thelever|06 against the ball valve 89 to force the valvecheck 85 oli 'its seat.When 't the valve check 85 is unseated, compressed air enters into thechamber 95, thence between the open valve check and its seat and throughthe ducts or passages 8l into the chamber 98, and

from there throughthe conduit I00 into the' cylinder II to force thepiston I6 downwardly,

which action trips the-clutch and permits the head of the press to movedownwardly. As' the piston I6 approaches the bottom of the cylinder Il,the axial extension II5 on the piston passes TheVV the mushroom heads 34through the opening |I6 and depresses the trip ar 19, to permit thelever |06 to move to the left about its pivot due to the movement of thevalve stem 86 as the check valve 85 is seated by the tension of spring94. 'I'his action will take place if theoperating valve B has beenseated and the air vented from the cylinder I8. The seating of the checkvalve shuts of! the supply of compressed air to the cylinder I1 andestablishes communication between said cylinder and the outer atmospherethrough the conduit |00, chamber 98, the ducts 81, the transversepassage 90a in the check valve stem and the lateral openings 90 in saidstem. The release of the cornpressed air from the chamber |1 permits thespring to move the clutch trip arm Il back into clutch-engagingposition, thereby preventing the tripping of the clutch until the piston|6 within the cylinder I1 is again moveddownwardly. Such downwardmovement, however, is not rendered possible until both manually operablevalves B are permitted to again seat, or, in other words, until theoperators hands are withdrawn from said valves and again vappliedthereto, This will be apparent, for when the operating valves B areopened in the manner specified, a puil or blast of air passes throughthe pneumatic circuit to act upon the piston in the pilot valveoperating means, and after so acting, the incoming air pressureoperates` to move the plunger valve 41 of the cut-out valve C againstthe seat 54 and said valve will remain seated so long as the left handoperating valve B is held open. When the hand is removed from the lefthand operating Valve B the check valve 25 therein will seat under theforce of the spring 26, the compressed air entrapped in the cult-outvalve C will vent through the opening 40 in said valve and permit theyplunger valve 41 to unseat.

When the hand is removed from the right hand operating valve B, the airfrom the cylinder I8 will vent through the opening 40 in said valve, thepiston B9 will be moved upwardly by spring 13, and the spring 6| willmove the bell-crank lever 15 about its pivot and return Cthe trip bar 19to its normal position.

If either of the manually operable valves B is tied down or held down,further operation of the press will be precluded, because, as abovedescribed, if the left hand valve B is held down, the plunger valve 41will remain seated and prevent the passage of air through the pneumaticcircuit; while if the right hand valve B is held down, the back pressurefrom the pilot cylinder will act upon the floating valve 60 to seat thesame, and as the effective area of the valve 60 acted upon by this backpressure is greater than the effective area of the seating face of thevalve, it will be apparent that a puff of incoming air through thecut-out valve C will be insufficient to unseat the valve 60. Hence, ifthe right hand` operating valve is tied down, the air will be trapped inthe cylinder I8 and when the trip bar is depressed by the pistonextension I I5, the trip bar will move to the right below the lever |06to hold the valve check 85 unseated,thus preventing the upward movementof clutch trip bar into clutch-engaging relation.

It will thus be seen that the safety device is eiective to preveritpress operation if any attempt is made by the p ress operator to haveone of his hands free during the tripping of the press.

Should it be desired to use the press for strip or roll feed duringwhich the hands of an operator need not be brought into proximity of theoperating press head', while at the same time provide a guarded point ofoperation during the commencement-*of the press operation. or where 'thesheet stock to be acted upon by the. press is of such size as to requirehandling by more than one operator, or by a single operator at somepoint other than in front of the press, it will be appreciated thatafter press adjustments have been made the press can be continuouslyoperated by providing a direct connection of air pressure to theinterior of the operating cylinder I1 whereby the clutch trip will beheld free of the clutch.

The safety device hereinbefore described, it will be appreciated, issubject to modification in constructional features and also subject tovarious uses within the range of engineering skill, without departingfrom the spirit of the' invention.

What I claim is:

1. Pneumatic safety control means for operation of a press or the like,comprising an air pressure responsive member, a pilot valve forcontrolling lthe admission to, and the venting from saidpressure-responsive member of compressed air, and a pneumatic circuithaving therein a cutout valve adapted to permit only a puff ofcompressed air to pass through the circuit, the pilot valve comprising athree-way valve having ducts vadapted for communication with thepressure- 2. Pressure safety control means for operationv of a press orthe like, comprising an air pressure responsive member, a pilot valvefor controlling the supply of compressed air to. said pressureresponsivemember, and a pneumatic circuit having therein at least three valves inseries, -two of which are manually unseatable and the third is a cut-outvalve disposed in the circuit between the two manually unseatable valvesand is adaptl ed to permit only a puff of compressed air to pass throughthe circuit when the manually tnseatable valves are sequentially orsimultaneously opened, Iand a pilot operating mechanism responsive toair pressure and operable by a puff of compressed air passing throughthe pneumatic circuit to open the pilot valve to admit compressed airfrom the supply source to the pressure-responsive member.

3. Pressure fluid control means for operation of a press or the like,comprising an air pressure responsive member, a pilot valve forcontrolling the admission to, and the venting from saidpressure-responsive member of compressed air, and -a pneumatic circuithaving therein at least three valves in series, two of which are with asource of compressed air, with the pressure-responsive memberand withthe atmosphere, and a pilot operating mechanism responsive to a puii.'oi' compressed air from the pneumatic circuit to-operate the three-wayvalve to admit compressed air from. the source to thepressure-responsive member, and means on the pilot operating mechanismoperable by the pressure-responsive member after it has been acted uponby the compressed air to openate the three-1 10 lway valve to permitventing 0i' the compressed air from the pressure-responsive member totheatmosphere. y l y 4. Pneumatic safety control means according to claiml, wherein the air pressure.V responsive member comprises aI cylinderhaving a piston therein which is movable by compressed air; wherein thethree-way valve is normally springseated to close the compressed airline and establish open communication between the interior oi' thecylinder and the atmosphere: and wherein the pilot operating 'mechanismincludes a cvlinder having a piston therein, a trip bar disposed betweenthe pilot cylinder and the threeway valve and through which trip bar thethree- 25 way valve is unseated. 5. Pneumatic safety control meansaccording to claim 1, wherein the air pressure responsive membercomprises a cylinder having a piston therein which is movable bycompressed air;

wherein the three-way valve is normally spring- 'seated to close thecompressed air line and establish open communication betweenthe-interior of the cylinder and the atmosphere: wherein the Ipilotoperating mechanism includes a cylinder having a piston therein, a tripbar disposed be tweenl the pilot cylinder and the three-way valve andthrough which trip bar the three-way valve is unseated; and wherein thepiston has means' movable therewith for engaging and tripping the 49trip bar to permit the three-way valve to again seat and re-establishcommunication between the cylinder and the atmosphere. ,Y

6. In combination with a press or the like having a movable head, ofpneumatic'safety control 45 means for operating said head, comprisingany operating cylinder having a piston therein capable oi' causingmovement of the movable head, a pilot valve for controlling theAadmission of compressed air to said cylinder to move the pis- 5 -tontherein. and a y pneumatic circuit having therein atleast three valvesin series, two of which are adapted to be "separatelymanually f unseatedlby the hands oi an 4operator and arev disposed at points well away'fromthe danger 55 `zone of movement of the. press head, and the third is acut-out valve disposed in the circuit between the other two valves, andadapted to vpermit only a pui! of compressed air tofpass through thecircuit, when the manually operable 0 valve nearest the pilot valve isunseated in ad'- vance of, or simultaneously with the other manu'- allyoperable valve. and a pilot operating mechanism comprising a pilotvcylinder and a pilot movable therein which is responsive to! pui! ofair from the ,pneumatic circuit to'l operate the pilot valve toadmitcompressed air from the supply source to the operating cylinder.

7. Pneumatic 'control means i'or operation of a power press or the likehaving Ia positiveacting clutch on the power shaft thereof, comprising aclutch-operating cylinder having an opening through its bottom, a pistonresponsive to iluid pressure movable in said cylinder and having anextension adapted to extend through the opening in the bottom of thecylinder, means movable by the movement oi the piston for tripping theclutch, anda spring-seated, three-way pilot valve having ducts adaptedfor communication with a source of compressed air, with the clutchoperating cylinder, and with the atmosphere, a pilot operating mechanismresponsivefto compressed air to unseat thel three-way valve to admitcompressed air from the source to the clutch-operating cylinder, saidpilot operating mechanism comprising a trip-bar, whichA is adapted to beengaged by the extension on` the piston after the latter has been movedby the compressed air entering the clutch-operating cylinderto permitseating oi' the three-way vinder under the influence of air pressure,said cylinder having an opening through' its bottom and the pistonhaving an extension adapted to extend through said opening, a three-waypilot valve having ducts adapted to alternately establish yiiuidcommunication `between a source of compressed air and the interior oi.'the cylinder. and between the interior o! othe cylinder and theatmosphere, huid-responsive pilot operating means vvcomprising a pivotedtrip bar adapted for operating the pilot valve to establish iluidcommunication betweenA the sourceoi' compressed air and the cylinder.and said trip bar being adapted to be tripped bythe extension on thepiston as it passes through the bottom of the y cylinder for operatingthe pilot valve .to estab-f lish huid communication between the interiorot the cylinder and thetatmosphere.

9. Pressure safety control means for operal -tion of a press or thelike, comprising a cylinder assembly unit consisting of a cylinder, aspringbiased piston movable within said cylinder under the influence ofair pressure, said cylinder having an' opening through its bottom andthe piston having an extension adapted to extend through said opening'when the piston is'moved by *air pressure in opposition to the spring,a normally spring-seated pilot valve for controllingthe lupply ofcompressed ,air to said cylinder. a pilot operating .mechanismresponsive 'to -airpressure comprising a pivoted trip bar adapted forunv seating the pilot valve lor-admitting compressed airi'rom the supplysource tothe cylinder, and further adaptedv to be .tripped by theextension on the piston to permit the pilot valve to reseat.

